1. Field of the Invention
The present invention relates to an image forming apparatus including an image reading section that reads a document image and an image forming section that records that document image on a sheet of paper.
2. Description of Related Art
Conventionally known is an image forming apparatus that reads an image of a document loaded on a platen or delivered through a paper conveying section, and records that image onto a sheet of paper or communicates it in the form of an image signal. One example of such an image forming apparatus is shown in FIG. 4. As shown in this figure, an image forming apparatus 10A includes: a body frame 11; a paper feeding section 50, an image forming section 60, and a fixing section 70 that are provided inside the body frame 11; an image reading section 40, a platen 12 formed of transparent glass, and a document conveying section 20 that are provided on top of the body frame 11. Inside the body frame 11, in an upper portion thereof, is provided a controller 13 that controls document conveyance operation, reading operation, image forming operation, and other operation, and in a middle portion thereof, is provided a paper ejecting section 80 equipped with an ejected paper tray 82.
The document conveying section 20 is openably mounted on the body frame 11 with a hinge section 20a provided on the far side of the plane of the figure. The document conveying section 20 includes: a document loading tray 21; a document feeding section 30; a document conveying path 27; and a document cover 29.
In the document loading tray 21, a pair of document guides 22 are so provided as to be slidable in the direction orthogonal to the document conveyance direction of the document loading tray 21; thus, a loaded document can be held in place corresponding to the size thereof on the tray without being displaced laterally. The ejected document tray 29a is formed integrally with the document cover 29 as part of the top face thereof. Thus, the document loading tray 21 forms the upstream-side end of the document conveying path 27, and the ejected document tray 29a forms the downstream-side end of the document conveying path 27. On the ejected document tray 29a, there are provided document displacement prevention members 28 composed of, for example, one 28a for A3 size, one 28b for A4 size, and one 28c for A5 size.
In the document feeding section 30, there are provided in order from the upstream side of the document conveyance direction along the document conveying path 27 a first document feeding roller 31, a second document feeding roller 32, a separation roller 33, a pair of first document conveying rollers, a pair of registration rollers 35, a pair of second document conveying rollers 36, a document guide 37, a pair of third document conveying rollers 38, and a pair of ejecting rollers 39. A document reading position 12a is set at a position facing the document guide 37 on the top face of the platen 12.
The first feeding roller 31 is so provided as to be movable up and down by unillustrated driving member such as a solenoid. When no document C is on the document loading tray 21, the feeding roller 31 is moved upward by the driving section based on a signal that is sent from a loaded document detecting member 21a, such as an optical reflection type sensor, provided on the document loading tray 21, to the controller 13. When a document C is loaded, the first feeding roller 31 is moved downward by the driving section and by its own weight so as to come into contact with the document C.
According to a stationary document reading method, a document (not illustrated) is loaded on a stationary document reading position 12b that is set on the top face of the platen 12, and is pressed by the document cover 29; thus, the document on the side having contact with the platen 12 is read by the image reading section 40.
The image reading section 40 includes: an exposure lamp 41; a reflecting plate 42; a first mirror 43; a second mirror 44; a third mirror 45; a collecting lens 46; and an image sensor 47 (e.g., line-type CCD). The exposure lamp 41 and the first mirror 43 are mounted on a carriage 48 and are made movable in the left/right directions in the figure.
The paper feeding section 50 includes a paper feeding cassette 51 and a paper feeding roller 52 provided in a lowest portion of the body frame 11. The paper feeding cassette 51 is for accommodating sheets of paper P. The sheets of paper P are fed out one after another into the conveying path 55 by the feeding roller 52 and are conveyed to the image forming section 60 by the pair of conveying rollers 53 and the pair of registration rollers 54.
The image forming section 60 includes: a photoconductive drum 61; an electrostatic charger 62 arranged near it; an optical scanning unit 63; a developing unit 64; a transfer roller 65; and a cleaner 66. The photoconductive drum 61 rotates in the clockwise direction in FIG. 4, so that first its surface is electrically charged uniformly by the electrostatic charger 62. Next, based on an electrical signal of the image that is read at the image reading section 40 and is sent through the controller 13, a laser beam is emitted from the optical scanning unit 63 onto the surface of the photoconductive drum 61, and consequently, on the paper P, a latent image is formed. The latent image is then supplied with toner and is developed as a toner image by the developing unit 64.
The sheet of paper P having the toner image transferred thereon is conveyed to the fixing section 70 composed of a heating roller 71 and a pressing roller 72, and the toner image is so heated and pressed as to be fixed onto the sheet of paper P there. Thereafter, the sheet of paper P is ejected by a pair of ejecting rollers 81 to the paper ejecting section 80 equipped with the ejected paper tray 82 with the surface of the paper having the image formed thereon facing that tray.
In the conventional image forming apparatus including the image reading section and the image forming section as described above, the image reading section needs to be mounted in a precise position relative to the image forming section fixedly housed inside the body frame. To increase the ease of maintenance of such apparatuses, there have been proposed some in which the image reading section is made openable with respect to the image forming section. For example, as disclosed in a patent publication (JP-B-3578109), by rotatably coupling together upper and lower units via a hinge member, it is possible to obtain an openable structure.
With this structure, for example, the image reading section disposed on the upper side is openable with respect to the image forming section disposed on the lower side, and this facilitates maintenance, replacement, and other work related to components inside the body frame and the apparatus itself.
However, if the rotatable part, namely the image reading section, is large and heavy, it cannot easily be placed at a precise position via the hinge member. Moreover, another problem will arise that the repeated opening and closing of the image reading section result in a change in the relative positional relationship with the image forming section.
Accordingly, there is a demand for a coupling structure in which upper and lower members are rotatably coupled with each other, and by which the upper, rotatable member is easily positioned even though it is heavy, and repeated opening and closing of the upper member does not lead to any change in the coupled posture or in the positions of the upper and lower members relative to each other.